Lending Activities - Credit quality of commercial mortgages (Details) $ in Millions	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 48,779	$ 46,677
Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,946	2,820
2021	3,030	2,708
2020	2,410	5,897
2019	5,532	5,989
2018	5,344	3,734
Prior	14,562	14,517
Total	$ 35,824	$ 35,665
Weighted average debt service coverage ratio	2.0	1.9
Weighted average loan-to-value ratio (as a percent)	57.00%	57.00%
Less than 65% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	$ 4,225	$ 2,286
2021	2,464	2,272
2020	2,171	4,149
2019	4,048	4,815
2018	3,667	2,892
Prior	10,418	9,902
Total	26,993	26,316
65% to 75% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	721	372
2021	329	410
2020	213	1,748
2019	1,484	1,174
2018	1,359	406
Prior	2,854	3,490
Total	6,960	7,600
76% to 80% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	237	0
2020	0	0
2019	0	0
2018	0	188
Prior	99	274
Total	336	462
Greater than 80% | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	162
2021	0	26
2020	26	0
2019	0	0
2018	318	248
Prior	1,191	851
Total	1,535	1,287
Greater than 1.2X | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,521	2,245
2021	2,318	1,662
2020	1,885	5,126
2019	5,056	3,926
2018	3,936	3,557
Prior	11,491	10,796
Total	29,207	27,312
1.00 - 1.20X | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	425	574
2021	712	1,019
2020	504	700
2019	424	1,138
2018	382	136
Prior	1,443	1,929
Total	3,890	5,496
Less than 1.00X | Commercial mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	1
2021	0	27
2020	21	71
2019	52	925
2018	1,026	41
Prior	1,628	1,792
Total	$ 2,727	$ 2,857